BACKGROUND: Medicinal herbs are used in poultry production to improve carcass quality, immunity and also lessen the use of antibiotics. OBJECTIVES: The aim of this study was to investigate the effect of adding coriander seed and ginger root powders to diet on performance, carcass traits, intestinal E.coli count and some serum biochemical parameters of broiler chickens. METHODS: One-hundred-sixty Cobb500 chicks were divided into four treatment groups with four replicates. Treatments as a completely randomized design were 1) basal diet (control), 2) basal diet plus 1.5% of coriander seed, 3) basal diet plus 0.75 %of ginger root powder, and 4) basal diet plus 1% coriander seed+ 0.5% of ginger root powder. At the end of the study, one bird from each replicate was slaughtered for blood sampling and carcass analysis. RESULTS: The results showed that the effect of treatments on feed conversion ratio of chickens was significant at during days 1-28 (p<0.05). The lowest feed conversion ratio was observed in coriander+ginger. Carcass analysis showed that the effect of treatments on abdominal fat weight, bourse and gizzard weights of chickens were significant (p<0.05). The greatest gizzard relative weight was in ginger+coriander group while the lowest abdominal fat and bourse relative weights were in ginger group. The treatments had significant effect on blood cholesterol and HDL concentrations (p<0.05). The lowest cholesterol level was observed in ginger group but the greatest HDL level was in coriander+ginger group. Effect of treatments on intestinal E.coli count was significant (p<0.05). Coriander+ginger treatment had the lowest E.coli in the ileum. CONCLUSIONS: The results showed that the level 0.75 ginger powder in broiler diets has positive effects on reduction of abdominal fat, bourse, cholesterol and also reduces the intestinal E.coli population. Ginger+coriander in the diet by reducing feed conversion ratio and population of E.coli caused an improvement in growth performance of broiler chickens.